bp2build: convert host & prebuilt header libraries

Test: bp2build.sh
Change-Id: If8165eac7c17c4eef3686067257aa792121db59d
diff --git a/cc/cc.go b/cc/cc.go
index 281ebc1..82b7c87 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -3476,9 +3476,7 @@
 				libraryBp2Build(ctx, c)
 			}
 		} else if !static && !shared {
-			if !prebuilt {
-				libraryHeadersBp2Build(ctx, c)
-			}
+			libraryHeadersBp2Build(ctx, c)
 		} else if static {
 			if prebuilt {
 				prebuiltLibraryStaticBp2Build(ctx, c)